Oxide Particles Research Articles

IrO2-ZrO2-SiO2 ternary oxide composites- based DSAs: Activity toward oxygen evolution reaction with long-term stability

BackgroundHigher purity of copper is produced by Electrowinning (EW) in the cathode. A major challenge in this technique is the anodic structure that causes in the energy consumption, corrosion resistance, and contamination of the copper produced in the cathode. MethodsTernary metallic oxide (IrO2-ZrO2-SiO2) composites with the different molar percentages of IrO2: SiO2 (10:60, 15:55, and 20:50%) were prepared on titanium substrate by the sol-gel technique, and then thermal decomposition to study the impact of IrO2 and SiO2 contents on the electrocatalyst performances of the dimensionally stable anodes (DSAs). The physicochemical properties of the DSAs were determined by X-ray diffraction (XRD), Field emission scanning electron microscope (FE-SEM), Atomic force microscopy (AFM), and electrochemical measurements. Significant findingsFE-SEM and AFM images display the impact of SiO2 on the crystallization and crystal growth of IrO2, leading to the formation of finer oxide particles and the porous morphology of the ternary oxide coatings. The DSA composed of 50 % SiO2 and 20 % IrO2 (IZS (20–30–50)) with a more porous surface area represented high apparent electrocatalytic activity toward the oxygen evolution reaction with long-term stability as analyzed under cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and accelerated lifetime (ALT) plots.

Physical Model of Inclusions Removal at Static Steel–Slag Interface

Inclusions are one of the important factors affecting the cleanliness of molten steel. The current optimization of inclusion removal methods mainly focuses on promoting inclusions to float to the slag–steel interface so that the inclusions can be absorbed and removed by the refining slag. However, the research on the floating removal of inclusions cannot be carried out directly in the ladle, so methods such as mathematical models and physical models were developed. This article uses silicone oil to simulate the slag layer; polypropylene particles; and aluminum oxide particles to simulate inclusions to establish a water model experiment. By changing the viscosity of silicone oil and the diameter of particles, the factors affecting the movement of inclusions at the slag–steel interface were explored. Based on the water model, a mathematical model of the floating behavior of inclusions at the slag–steel interface was constructed, and parameters such as particle diameter and interfacial tension in the water model experiment were studied by the mathematical model for calculation. Both the mathematical model and the water model experimental results show that after the viscosity of silicone oil increases from 0.048 Pa·s to 0.096 Pa·s, the dimensionless displacement and terminal velocity of the particles decreases. When the diameter of the same particle increases, the dimensionless displacement and terminal velocity increases. The dimensionless displacement of polypropylene particles of the same diameter is larger than that of aluminum oxide particles, and the terminal velocity is smaller than that of aluminum oxide particles. This is attributed to the better overall three-phase wettability of polypropylene particle. When the liquid level increases, the dimensionless displacement and terminal velocity of particles under the same conditions show only slight differences (less than 10%).

High-Temperature Cyclic Oxidation Behavior and Microstructure Evolution of W- and Ce-Containing 18Cr-Mo Type Ferritic Stainless Steel

Due to the recurrent starting and stopping operations of automobiles during service, their engines’ hot ends are continually subjected to high-temperature cyclic oxidation. Therefore, it is crucial to develop ferritic stainless steels with better high-temperature oxidation resistance. This study focuses on improving the high-temperature cyclic oxidation performance of 18Cr-Mo (444-type) ferritic stainless steel by alloying with high-melting-point metal W and the rare earth element Ce. For this purpose, a high-temperature cyclic oxidation experiment was designed to simulate the actual service environment and investigate the high-temperature cyclic oxidation behavior and microstructure evolution of 444-type ferritic stainless steel alloyed with W and Ce. The oxide structure and composition formed during this process were analyzed and characterized using scanning electron microscopy/energy dispersive spectroscopy (SEM-EDS) and electron probe X-ray micro-analyzer (EPMA), in order to reveal the mechanism of action of W and Ce in the cyclic oxidation process. The results show that 18Cr-Mo ferritic stainless steel alloyed with W and Ce exhibits an excellent resistance to high-temperature cyclic oxidation. The element W can promote the precipitation of the Laves phase between the matrix and the oxide film, and the small-sized Laves phase can inhibit the interfacial diffusion of oxidation reaction elements and prevent the inward growth of the oxide film. The element Ce can refine oxide particles and reduce the thickness of the oxide film. CeO2 particles within the oxide film can serve as nucleation sites for the formation of oxide particles from reactive elements, and they also contribute to pinning the oxide film, thereby enhancing its adhesion.

Enhancing the conversion of waste motor oil into diesel-like fuels using mineral-impregnated biochar catalysts

This study shows how the presence of metal-impregnated biochar influences the kinetics of the catalytic conversion of waste motor oil (WMO) into a diesel-like fuel (DLF). First, the initial metal concentration in the wet impregnation process was optimized, showing that high metal concentrations tend to clog the biochar pores, reducing the reaction’s conversion and speed. Zinc and calcium showed higher kinetic constants at the optimized conditions than nickel, while the yield- and selectivity-to-liquid products were unaffected. Then, a reduction method was developed for impregnating metal particles of calcium oxide to enhance the metal dispersion at the biochar surface. This material showed the best performance in the reaction due to the presence of small particles instead of metal agglomerates. An increase of about 280% in the kinetic constant at 420 °C and a much lower activation energy (246 kJ mol−1) compared to the thermal cracking (308 kJ mol−1) was obtained. Finally, the DLF from the best catalytic system was analyzed. Interestingly, the fuel showed similar rheological properties to commercial diesel with a similar hydrocarbon distribution but with the presence of smaller hydrocarbon chains.

On the Methodology of the Quantitative Analysis of Fe–Cr–Mn–Mo–N–C Steels Reinforced with Oxide and Nitride Particles Using an Energy Dispersive X-Ray Fluorescence Spectrometer BRA-135F

On the Methodology of the Quantitative Analysis of Fe–Cr–Mn–Mo–N–C Steels Reinforced with Oxide and Nitride Particles Using an Energy Dispersive X-Ray Fluorescence Spectrometer BRA-135F

The Effects of Cl− and selected deoxidizers on the high temperature corrosion electrochemistry of alloy 690 in nuclear steam generator water

ABSTRACT The heat transfer tube in a steam generator serves as a critical heat exchange component in the primary and secondary loops of pressurized water reactor (PWR) nuclear power plants. The corrosion resistance of the heat transfer tube material directly influences the longevity of PWR nuclear power plants. This study investigated the electrochemical corrosion properties of 690 alloy (UNS N06690) in a simulated secondary water environment of PWR, focusing on different chloride ion concentrations and combinations of deoxidizers. The findings reveal a gradual decrease in the corrosion potential of 690 alloy, accompanied by an increase in self-corrosion current and a progressive reduction in the passivation range, ultimately leading to its disappearance as chloride ion concentration rises from 0 μg·L−1 to 500 μg·L−1. Moreover, the impedance value of the inner film exhibits a declining trend with increase of chloride ion concentration. Conversely, the resistance value of the outer film remains relatively stable while the size and spacing of oxide particles on the surface of the 690 alloy continuously increase. This observation suggests that chloride ions primarily influence the formation of the inner passivation film, which in turn determines the corrosion resistance of the 690 alloy. Notably, the performance of the 690 alloy is similar when the deoxidizer combination is ammonia(NH3)+erythorbic acid(ERA) or NH3+hydrazine(N2H4), demonstrating the ability to form a relatively complete passivation film and exhibit improved corrosion resistance compared to NH3+N-isopropyl hydroxylamine, additionally, when the deoxidizer combination is NH3+N2H4, the 690 alloy exhibits lower self-corrosion current density across different chloride ion concentrations, indicating enhanced corrosion resistance.

Effect of pressure, Mg content and AP size on the microscale flame structure of Mg-based propellant

The Mg-based propellant is considered to be a promising fuel for underwater propulsion, but the mechanism of the change of the burning rate is unclear. The Mg-based propellant was divided into two parts on the basis of the BDP multi-flame model: large-size oxidizer particle and pseudo-propellant consisting of fine oxidizer and other components, and the micro steady-state combustion model of Mg-based propellant was established. Quantitatively analysis on the gas-phase multi-flame structure was performed, which focused on the effect of pressure, Mg content, and oxidizer particle size on the burning rate. This model was verified by the results of combustion experiments on ammonium perchlorate (AP) /hydroxyl-terminated polybutadiene (HTPB) composite propellant and Mg-based propellant, and the mean absolute percentage error between the burning rate obtained from the simulation and the experimental measurements was less than 5%. Results indicated that the flame structure of Mg-based propellant exhibited typical BDP flame characteristic. As pressure increased from 1 MPa to 4 MPa, the premixed AP flame and the preliminary diffusion flame were closer to the burning surface, which enhanced the heat feedback. And accordingly, the burning rate raised from 5.93 mm/s to 9.79 mm/s. Mg content mainly affect the combustion process of the pseudo-propellant. The premixed flame above the pseudo-propellant gradually disappeared as the Mg content increased from 15% to 63%, which led the burning rate to decrease from 17.45 mm/s to 7.83 mm/s. AP particle size affected the effectiveness of the preliminary diffusion flame on the burning surface and resulted in a change in the burning rate. These findings can provide theoretical guidance for the design of Mg-based propellant formulations.

Nanocrystalline Y2O3-modified metal matrix composite coatings with improved resistance to thermocyclic oxidation and V2O5-induced type II hot corrosion

Incorporating reactive elements (RE) into turbine coatings is a well-established surface treatment. However, suboptimal RE concentrations can lead to compromised strength, heightened brittleness, and reduced adhesion. In contrast, RE oxides offer advantages of avoiding these detrimental effects, counteracting corrosion phenomena induced by V2O5 compounds and enhancing oxidation resistance. A notable challenge lies in optimizing RE oxide particle incorporation and understanding the influence of particles in coating microstructures. This study focuses on developing NiAl and Ni-Cr-Al type metal matrix composite (MMC) coatings on Inconel 617 (IN617), containing up to 11 vol% of Yttria (Y2O3) nanoparticles. Y2O3 nanoparticles and Ni were co-electrodeposited on IN617 followed by either pack aluminizing or a two-step chromizing and aluminizing process. An even distribution of Y2O3 nanoparticles was observed throughout the entire 100 μm coating thickness, leading to significant grain refinement in the sub-micron to nano range in both coating types. Y2O3-strengthened coatings were subjected to oxidation at 1100 °C and hot corrosion at 700 °C and were compared to their Y2O3-free counterparts. Present at grain boundaries, Y2O3 markedly enhanced the oxidation and corrosion resistance by reducing interdiffusion, improving the oxide scale adherence and binding V2O5, highlighting the potential of this method for advanced turbine blade coatings.

Facile fabrication of 3D-α-Fe2O3@2D-g-C3N4 heterojunction composite materials: Effect of iron oxide loading on the electrochemical performance

Designing heterojunction nanocomposites is crucial for optimizing supercapacitor electrodes. This study addresses the challenge by introducing a facile synthesis method for creating 3D-α-Fe2O3@2D-g-C3N4 heterojunctions through a bulk carbon nitride-assisted hydrothermal process. During this process, the growth of ferric oxide particles coincides with the exfoliation and deposition of carbon nitride, leading to simultaneous structural changes in both iron oxide and carbon nitride phases. The resulting composite's properties strongly correlate with the iron oxide loading. Comprehensive characterization using XRD, FTIR, SEM-EDAX, XPS and TEM identified three distinct structures for α-Fe2O3/g-C3N4 composites based on iron oxide loading: low, medium, and high. The medium-loaded sample demonstrated superior electrochemical performance, attributed to better interfacial contact and the formation of 3D-Fe2O3@2D-g-C3N4 heterojunctions. This composite, with an optimized 22 wt% iron oxide loading, exhibited a maximum specific capacitance of 925.1 Fg−1 at 5 mVs−1 and 498.6 Fg−1 at 6 Ag−1 in charge-discharge analysis, with stable performance over 2000 cycles. Overall, this research presents an enhanced hydrothermal method for facile preparation of effective α-Fe2O3/g-C3N4 heterojunction materials.

Determination of effective liquid-phase diffusion coefficients by tracer method in continuous packed columns

Many industrially relevant chemical processes are affected by the liquid-phase diffusion resistance in porous materials, for example in heterogeneous catalysts. Therefore, reliable experimental methods for the determination of effective diffusion coefficients in porous structures are highly desirable. In this work, a method was developed to study the internal diffusion effects in porous media by step response experiments with tracers injected to fixed beds filled with porous particles and inert material. The tracer responses were recorded at the outlet of the bed by UV–vis spectrometry. Ethanol was used as the tracer and water as the solvent. Porous aluminum oxide particles were selected as the model material. The step responses were described with a dynamic axial dispersion model, i.e. partial differential equations for the inert and catalyst sections of the bed. The partial differential equations describing the model were discretized with finite differences and the resulting ordinary differential equations were solved numerically with a solver for stiff ordinary differential equations. From the experimental data, the dispersion coefficients of the bed and the effective diffusion coefficient in the porous aluminum oxide particles were successfully determined by non-linear regression analysis. The values of the effective diffusion coefficents had a good agreement with the liquid-phase diffusion coefficients estimated from correlations. The method is applicable for any porous material.

Investigation of Mechanical Properties of Polymer-Infiltrated Tetrapodal Zinc Oxide in Different Variants.

The aim of this study was to evaluate the influence of weight ratio, the shape of the precursor particles, and the application of a phosphate-monomer-containing primer on the mechanical properties of polymer infiltrated ceramic networks (PICNs) using zinc oxide. Two different types of zinc oxide particles were used as precursors to produce zinc oxide networks by sintering, each with two different densities resulting in two different weight ratios of the PICNs. For each of these different networks, two subgroups were built: one involving the application of a phosphate-monomer-containing primer prior to the infiltration of Bis-GMA/TEGDMA and one without. Elastic modulus and flexural strength were determined by using the three-point bending test. Vertical substance loss determined by the chewing simulation was evaluated with a laser scanning microscope. There was a statistically significant influence of the type of precursor particles on the flexural strength and in some cases on the elastic modulus. The application of a primer lead to a significant increase in the flexural strength and in most cases also in the elastic modulus. A higher weight ratio of zinc oxide led to a significantly higher elastic modulus. Few statistically significant differences were found for the vertical substance loss. By varying the shape of the particles and the weight fraction of zinc oxide, the mechanical properties of the investigated PICN can be controlled. The use of a phosphate-monomer-containing primer strengthens the bond between the infiltrated polymer and the zinc oxide, thus increasing the strength of the composite.

Cyclic reduction of combusted iron powder: A study on the material properties and conversion reaction in the iron fuel cycle

Recently, iron powder has been proposed as a high energy density, easily storable, and CO2-free energy carrier. During the iron combustion, thermal energy is released as heat. The combusted products, the iron oxide particles, are captured and cyclically reduced back into iron powder in a process that is powered by renewable energy. Each combustion step, followed by a reduction, constitutes one cycle in the process. Previous studies predominantly focused on the reduction and combustion as individual steps. This work investigates the impact of cyclic combustion-reduction on material properties, with the specific focus on the reduction of iron oxides using hydrogen under fluidisation conditions. The powder is combusted and reduced for 3 cycles under the same conditions. Afterwards the properties of the powder and the reaction conversion are characterized. The physical techniques used for size and shape analysis include laser diffraction particle size analysis and scanning electron microscopy (SEM). For structure and chemistry, X-ray diffraction (XRD) and energy dispersive X-ray (EDX) analysis are also employed. To study the effect of the reduction conditions on the cycle and on the material properties of the powder, different experiments are conducted using 550 and 575°C as reduction temperatures. The higher conversion is observed at 575°C. During the first combustion particles resulted in large agglomerates and required a manual grinding step before being sent to the next reduction. However, the particle size distribution remains relatively stable in all subsequent cycles. The results suggest that the powder can be effectively utilized in the iron fuel cycle without requiring additional intermediate treatments, such as grinding and sieving after each cycle. This aspect highlights the potential feasibility and simplicity of implementing the cyclic combustion-reduction process for practical applications of iron powder as an energy carrier.

Fabrication of Multifunctional Nanocomposite Fiber Extracted from Sambucus nigra: Anti-nociceptive, Anti-inflammatory, Self-Cleaning, and UV Blocking.

This article describes how to extract chemical compounds from Sambucus nigra and make multifunctional nanofabric doping/undoping nano-zinc oxide particles using an electrospinning apparatus. The created sample was examined using field emission scanning electron microscope (FESEM), which revealed that the manufactured fibers have an approximate diameter of 35nm. An elemental mapping study also demonstrated the excellent distribution of nano-ZnO over the surface of the nanocomposite. The anti-nociceptive effect of the samples was studied, and the results suggested that the presence of Sambucus nigra caused pain prevention, and this effect demonstrated the anti-nociceptive effect in the samples studied by tail-flick experiments. Additionally, the anti-inflammatory properties of the samples were tested and showed favorable data results. Meanwhile, the self-cleaning of the prepared nanocomposites was studied. The results show that nano-zinc oxide doping has a direct impact on improving self-cleaning properties. Furthermore, ultraviolet (UV) transmission analysis of the samples showed that the prepared nanocomposites had excellent UV-blocking properties.

Wet combustion synthesis of new thermochemical energy-storage materials based on carbide slag/magnesium oxide using citric acid

In this study, industrial solid waste carbide slag (as the calcium source) is modified using the critic acid (as the fuel) combustion mixing method to prepare a new type of magnesium oxide–doped energy-storage material. The experimental results show that the prepared H2O-CM-100 material doped with magnesium oxide exhibits good energy-storage performance and cycling stability during calcium cycling. After 20 energy-storage cycles, the energy-storage density and effective conversion rate remained stable at 1800 kJ/kg and 0.57, respectively. These values exceed the reported energy-storage densities and effective conversion rates of carbide slag energy-storage materials modified using the dry physical mixing method employed in previous studies. In addition, the carbonation kinetics results indicate that the doping of magnesium oxide effectively improves the carbonation reaction rate of carbide slag materials in the carbide slag cycle. In summary, magnesium oxide doping can not only improve the sintering of calcium oxide particles in carbide slag materials but also effectively enhance the energy-storage performance and carbonation reaction rate of carbide slag during carbide slag cycles. Thus, this study proposes a novel method for the efficient resource utilization of carbide slag and development of energy-storage materials.

Repeated Injection of Very Small Superparamagnetic Iron Oxide Particles (VSOPs) in Murine Atherosclerosis: A Safety Study.

Citrate-coated electrostatically stabilized very small superparamagnetic iron oxide particles (VSOPs) have been successfully tested as magnetic resonance angiography (MRA) contrast agents and are promising tools for molecular imaging of atherosclerosis. Their repeated use in the background of pre-existing hyperlipidemia and atherosclerosis has not yet been studied. This study aimed to investigate the effect of multiple intravenous injections of VSOPs in atherosclerotic mice. Taurine-formulated VSOPs (VSOP-T) were repeatedly intravenously injected at 100 µmol Fe/kg in apolipoprotein E-deficient (ApoE KO) mice with diet-induced atherosclerosis. Angiographic imaging was carried out by in vivo MRI. Magnetic particle spectrometry was used to detect tissue VSOP content, and tissue iron content was quantified photometrically. Pathological changes in organs, atherosclerotic plaque development, and expression of hepatic iron-related proteins were evaluated. VSOP-T enabled the angiographic imaging of heart and blood vessels with a blood half-life of one hour. Repeated intravenous injection led to VSOP deposition and iron accumulation in the liver and spleen without affecting liver and spleen pathology, expression of hepatic iron metabolism proteins, serum lipids, or atherosclerotic lesion formation. Repeated injections of VSOP-T doses sufficient for MRA analyses had no significant effects on plaque burden, steatohepatitis, and iron homeostasis in atherosclerotic mice. These findings underscore the safety of VSOP-T and support its further development as a contrast agent and molecular imaging tool.

A Versatile Synthesis Platform Based on Polymer Cubosomes for a Library of Highly Ordered Nanoporous Metal Oxides Particles.

Polymer cubosomes (PCs) have well-defined inverse bicontinuous cubic mesophases formed by amphiphilic block copolymer bilayers. The open hydrophilic channels, large periods, and robust physical properties of PCs are advantageous to many host-guest interactions and yet not fully exploited, especially in the fields of functional nanomaterials. Here, the self-assembly of poly(ethylene oxide)-block-polystyrene block copolymers is systematically investigated and a series of robust PCs is developed via a cosolvent method. Ordered nanoporous metal oxide particles are obtained by selectively filling the hydrophilic channels of PCs via an impregnation strategy, followed by a two-step thermal treatment. Based on this versatile PC platform, the general synthesis of a library of ordered porous particles with different pore structures , tunable large pore size (18-78nm), high specific surface areas (up to 123.3m2g-1 for WO3) and diverse framework compositions, such as transition and non-transition metal oxides, rare earth chloride oxides, perovskite, pyrochlore, and high-entropy metal oxides is demonstrated. As typical materials obtained via this method, ordered porous WO3 particles have the advantages of open continuous structure and semiconducting properties, thus showing superior gas sensing performances toward hydrogen sulfide.

Improving dispersibility of tungsten oxide particles with organic ligands for photochromic films

Tungsten trioxide (WO3) has been studied as a promising photochromic material due to its favorable properties such as low manufacturing cost, high thermal and photostabilities, and low toxicity. Nevertheless, its practical application has been hindered by a relatively slow bleaching rate compared to other photochromic materials. Furthermore, metal oxide particles such as tungsten oxide face challenges in dispersing within process solvents, leading to difficulties in solution-based film fabrication processes. In this study, we aimed to address this limitation by exploring novel approaches to enhance both the dispersibility of tungsten oxides in processing solvents and their photochromic properties. To achieve this, we synthesized tungsten oxide composites by introducing various organic ligands, including polyvinylpyrrolidone (PVP), oleylamine (OA), hexadecylamine (HDA), and cetyltrimethylammonium bromide (CTAB). Through a comparative analysis, we found that the introduction of organic ligands significantly improved the dispersibility of tungsten oxides in processing solvents, while also enhancing their photochromic properties, including bleaching rate. Notably, the PVP ligand demonstrated superior performance in enhancing the overall properties of tungsten oxide composites. Our findings provide insights into the optimization of tungsten oxide-based photochromic materials for practical applications, offering potential directions for improvement and proposals for enhancing their performance and broadening their utility in various fields.

Synthesis and characterization of modified iron oxide hydrophobic corrosion-resistant pigment for aluminum alloy coating

A hydrophobic coating containing modified iron oxides was prepared for corrosion protection of aluminum alloy. The modified iron oxide particles were synthesized using the annealing method and the evaluation of the corrosion-resistant benefits of modified iron oxides as additive in the epoxy resin coating was conducted. The raw FeOOH phase can be transformed into the α-Fe2O3 phase by increasing the annealing temperature. The morphology, colors, and pore size of the modified iron oxide are controllably evolved via finely adjusting the annealing temperature, which is beneficial for the compatibility, dispersion, and stability with epoxy resin. Besides, modified α-Fe2O3 annealed at 700 °C exhibited elliptical morphology and good solubility in epoxy resin solvents to form a hydrophobic corrosion inhibition layer (TP700), which further improves the corrosion resistance. Findings of corrosion electrochemical measurements and salt spray test confirmed the existence of TP700 composite coating resulted in the best corrosion protective properties on aluminum alloy during the corrosion process with the minimum corrosion current of 7.75 × 10−10 A cm−2 and the maximum |Z|0.01Hz value of 1.80 × 108 Ω cm2, which both are about two orders of magnitude higher than the commercial Fe2O3. Our results suggest a new venue for preparing modified iron oxide pigment on the surface of aluminum alloy materials for enhanced anti-corrosion applications.

Heat-resistant super-dispersed oxide strengthened aluminium alloys.

Oxided-dispersion-strengthened (ODS) alloys are promising high-strength materials used in extreme environments such as high-temperature and radiation tolerance applications. Until now, ODS alloys have been developed for reducible metals by chemical processing methods, but there are no commercially available ODS alloys for unreducible metals, namely, Al, Mg, Ti, Zr and so on, owing to the challenge of uniformly dispersing oxide particles in these alloys by traditional techniques. Here we present a strategy to achieve ODS Al alloys containing highly dispersive 5 nm MgO nanoparticles by powder metallurgy, using nanoparticles that have in situ-grown graphene-like coatings and hence largely reduced surface energy. Notably, the densely dispersed MgO nanoparticles, which have a fully coherent relationship with an Al matrix, show effective suppression of interfacial vacancy diffusion, thus leading to unprecedented strength (~200 MPa) and creep resistance at temperatures as high as 500 °C. Our processing approach should enable the dispersion of ultrafine nanoparticles in a wide range of alloys for high-temperature-related applications.

Mn-doped Sequentially Electrodeposited Co-based Oxygen Evolution Catalyst for Efficient Anion Exchange Membrane Water Electrolysis.

Designing high-performance and durable oxygen evolution reaction (OER) catalysts is important for green hydrogen production through anion exchange membrane water electrolysis (AEMWE). Herein, a series of Mn-doped Co-based OER catalysts supported on FeOxHy (FCMx) are presented to enhance the OER activity. Mn doping effectively reduces the size of the Co oxide particles, thereby augmenting the active surface area. Moreover, Mn doping induces the creation of oxygen vacancies, leading to an efficient structural conversion during the OER, which is confirmed via in situ Raman spectroscopy. Under optimal conditions, the catalyst exhibits an overpotential of 234.4 mV at 10 mA cm-2 and a Tafel slope of 37.2 mV dec-1 under half-cell conditions. The AEMWE single-cell system demonstrates a current density of 1560 mA cm-2 at 1.8 V at 60 °C with a degradation rate of 0.4 mV h-1 for 500 h at 500 mA cm-2. Our development of a robust OER catalyst represents notable progress in the field of nonprecious-metal water electrolysis, marking a step toward cost-effective green hydrogen production.